Measurement of inclination of an object provides a lot of useful information in relation to the physical conditions of the object. For example, the measurement of tilting of a structure, such as a bridge or a building, provides useful information on the safety and stability of the structure.
Tilt measurement apparatus are generally categorized as the “contact-type” or the “non-contact type”. In the contact-type apparatus, a sensor is usually mounted on an object the inclination of which is to be measured. An example of the contact-type tilt measurement apparatus is descried in U.S. Pat. No. 5,218,771. However, it is not always possible or practical to use a contact-type tilt measurement apparatus. For example, it is frequently necessary to measure the relative tilting of various components mounted or to be mounted on a printed circuit board during or after the assembly process. Due to the high through-put demand or the high-density nature of the mounting of various components, the contact-type tilt measurement sensor is usually neither appropriate nor practical. On the other hand, a non-contact-type tilt measurement apparatus requires no mounting and/or dismounting of sensors on individual components which form part of a larger scale component integration. Therefore, the non-contact-type tilt measurement apparatus is especially suitable for such high through-put and high-density packaging environment.
Therefore, it would be advantageous to provide a non-contact-type tilt measurement apparatus which mitigates or alleviates shortcomings of the contact-type tilt measurement apparatus.